Tubman won a narrow victory with 33.6 percent of the votes cast, just over 7,000 more than former First Lady Eleanor Roosevelt, who received received 31.5 percent of the 352,431 votes cast in the final round. Next came civil rights icon Rosa Parks and Cherokee Nation Principal Chief Wilma Mankiller, who were separated by just 5,470 votes for third and fourth place.

"Our paper bills are like pocket monuments to great figures in our history," said Women On 20s Executive Director Susan Ades Stone. "Our work won't be done until we're holding a Harriet $20 bill in our hands in time for the centennial of women's suffrage in 2020."

In addition to the petition, the group will ask supporters to join a "virtual march" by sending the president messages of support for their cause using the hashtag #DearMrPresident.

Mr. Obama himself has weighed in on the proposal, calling it a "pretty good idea."

The group's efforts have inspired legislation in Congress as well. New Hampshire Sen. Jeanne Shaheen, a Democrat, introduced the Women on the Twenty Act which would require the Treasury to "convene a panel of private citizens" to recommend a woman to be printed on the $20 Federal Reserve notes, according to the text of the bill.

"Our paper currency is an important part of our everyday lives and reflects our values, traditions and history as Americans," Shaheen said in a statement. "It's long overdue for that reflection to include the contributions of women."

When she announced the bill, Shaheen tipped her hat to the Women On 20s campaign, although the group did not work with her office.